This invention relates to vaccines for immunization against group A and group C meningococcal meningitis. More particularly, it relates to a method for removing endotoxin contaminants from meningococcus group A and group C polysaccharides which are useful as vaccines.
The use as vaccines of antigenic group specific polysaccharides isolated from serologic group A and group C meningococci is known in the art and is disclosed, for example, in U.S. Pat. No. 3,636,192 to Gotschlich which disclosure is hereby incorporated by reference. A problem associated with the preparation of such vaccines, however, is the removal of endotoxin contaminant. Prior art methods resulted in significant losses of polysaccharides. For example, removal of endotoxin contaminant by ethanol treatment results in losses of polysaccharide as high as 70%.
It is, accordingly, an object of the present invention to provide an improved method for the removal of endotoxin contaminant from meningococcus group A and group C polysaccharides used as vaccine. Another object is to provide a method for removal of endotoxin contaminant which minimizes loss of polysaccharides. These and other objects of the present invention will be apparent from the following description.